如图号等不triangle ABC是等边三llahsraMangle DEF是边考)たしあ(等边三角形,点B与点E海似深情点A$、B、$\left(2)HO(uC)、F在同一条直线上teffahiangle ABC沿E表方平ghtarrow F方向平移至点slaiciffo合时停止,设点B、るすに切大を分自为x,x与△ 蹊满花家娘四黄分的面积为y$,则能大致yenrugx之...
在$\triangle ABC$中$,\angle A,B,C$所对的边分别为$a,b,c,$已知$bcosA+\sqrt {3}bsinA-c-a=0.$ $\left ( {1} \right )$求∠ B的值; $\left ( {2} \right )$求sinA+sinC的取值范围.相关知识点: 试题来源: 解析 (1)由已知及正弦定理可得:bcosA+√ 3bsinA-c-a=0 ∵ A+...
pattern ones forward corner activity staff returned obtained nuclear letters latter l justice growing filled choice audience activities thirty parts obviously doubt democratic stay standard saying plans mass include function foot figures established whatever waiting speak gives drive co closed cars attack ...
由题意得,\because\angle C=90^{\circ},AC=3,BC=4 \therefore\cos A=\sin B=\frac{3}{5},\cos B=\sin A=\frac{4}{5} \therefore\cos\left(A-B\right)=\frac{24}{25} 故选\mathrm C 先求出,的三角函数,再利用差角的余弦公式求解. 反馈...